Isopongaglabol and 6-methoxyisopongaglabol,two new hydroxyfuranoflavones from Pongamia glabra

Isopongaglabol and 6-methoxyisopongaglabol, two new hydroxyfuranoflavones, together with two furanoflavones 5-methoxyfurano(8,7-4″,5″)flavone and 5-methoxy-3′,4′-methylenedioxyfurano(8,7-4″,5″)flavone, two simple flavones, desmethoxykanugin and fisetin tetramethyl ether, a chromenoflavanone, ovalichromene B, two triterpenes, cycloart-23-ene-3β,25-diol and friedelin, and β-sitosterol-β-d-glucoside were isolated from the petrol and CHCl₃ extracts of the flowers of Pongamia glabra. The structures of isopongaglabol and 6-methoxyisopongaglabol have been established as 4′-hydroxyfurano(8,7-4″,5″)flavone and 4′-hydroxy-6-methoxyfurano(8,7-4″,5″)flavone, respectively, on the basis of the spectral evidence and they have been confirmed by synthesis.     

Naltrexone reduces weight gain, alters “β-endorphin”, and reduces insulin output from pancreatic islets of genetically obese mice

Naltrexone, an opiate antagonist, was administered to young obese (ob/ob) and lean mice for five weeks. Animals had continuous access to food and received 10 mg/kg SC twice daily with equivalent volumes of saline given to controls. The effects on body weight, and pituitary and plasma levels of β-endorphin-like material were measured. Naltrexone-injected obese animals gained weight more slowly over the first three weeks while the weight gain of lean animals was not affected by naltrexone. Plasma levels of β-endorphin were shown to be significantly higher in untreated ob/ob mice and this difference increased with age (4–20 weeks). With naltrexone treatment, plasma levels in +/? mice rose and exceeded those in ob/ob. Saline treatment appeared to be a stress, and pituitary β-endorphins rose 4–6 fold in ob/ob compared with +/?. While naltrexone reduced the levels in ob/ob pituitary towards normal, no effect on β-endorphin levels in pituitary of lean mice was obtained. In vitro studies of effects of the opiate antagonists, naloxone, on insulin secretion by isolated islets provided additional evidence of resistance of lean mice to naloxone relative to ob/ob. (IRI secretion fell only in naloxone treated ob/ob islets.) These observations support the contention that this form of genetic obesity is characterized by elevated endogenous opiate levels and an increased sensitivity to opiate antagonists such as naltrexone or naloxone.     

Actin organization and fibrin-clot retractile activity of cultured mouse fibroblasts

Summary It is known that human and animal fibroblasts are able to induce the retraction of a fibrin clot. In the present study the correlation between (i) fibrinclot retractile (FCR) activity, (ii) the number of actin stress-lines in mouse fibroblasts during growth in culture, and (iii) the sensitivity of actin stress-lines to a powerful actin-depolymerizing factor (ADF), present in plasma and serum of humans and laboratory animals was investigated. Fibroblasts at early passages (2–4) were tested for these parameters at various intervals after seeding (24, 96, and 168 h). The number of actin stress-lines was progressively higher, while the sensitivity to ADF action was progressively lower in cells cultured from 24 to 168 h; the FCR capacity was significantly decreased at 168 h. These data suggest that cells containing weakly polymerized and/or stabilized actin are more active than those containing highly polymerized and/or stabilized actin in triggering fibroblast contraction.     

NMR studies of prebiotic polypeptides

Several polypeptides prepared by means of pyrocondensation have been the subject of structural investigations. Attention has been focused on the constitutional characterization of homo-and co-polymers containing Asp and Glu residues, whose role is essential for the formation of the so-called proteinoids. Contrary to the literature data based on chemical degradation, nmr studies show conclusively that in thermal poly-aspartic acid only β-peptide linkages are present. This result casts serious doubt on the role thermal condensation might have played in prebiotic polypeptide syntheses.